In an article of footwear, such as shoe or a boot, it is sometimes necessary to use a removable insole. An insole will reduce the inner volume of the shoe, for better fit of the foot into the slightly too large shoe. If the insole is previously treated with appropriate chemicals, it may counter bad odours generated by the foot. The insole may induce some ventilation in the shoe, and increase comfort of the foot due to its cushioning effect. The insole may also increase the useful lifespan of the shoe, by absorbing the moisture generated by the foot, said moisture comprising chemical compounds that are damaging in the long run to the shoe material.
Broadly speaking, conventional removable insoles are made of a single sheet of material, conforming to the shape of the sole of the foot. In the prior art, means have been proposed to prevent some lateral or fore and aft sliding of the insole in the shoe: see Canadian Pat. No. 563,653. Also, further means have been suggested for providing a contoured insole, whereby the portions of the insole in register with the side edges and the ball of the foot are thicker, for better comfort: see U.S. Pat. No. 2,790,254.
All these insoles are to be used as such: either they are used, or they are removed from the shoe. This is inefficient, in that a manufacturer will have to make up a large number of variably dimensioned such insoles, to satisfy his clientele. Moreoever, these known insoles have no means whereby minute adjustments of their thickness may be possible.
And what is more, there are some persons who face a great deal of difficulty in finding the shoe of the appropriate dimensions, since they have relatively narrower or larger or shorter or longer feet, or have slightly different foot contour than those fitting standardized shoe sizes. Such persons may have to pay more than others for their shoes, since they require custom made ones, while conventional insoles are of no help to them.